第一,并不是每个女人的周期是28天。
第二,本人曾听过一个polygamist的seminar. The speaker, a lady attorney, is the 7th wife of a man who has got nine. People popped the same question: how do you guys manage your love life? Basically, the wives make appointments with the man. She is very proud of the fact that her husband granted her way more appointments than others.
>娶姨太太也是一门高深的学问啊。
You don't need a PhD to be a polygamist. It won't help. It will only make it worse. Probably, he can probably publish papers on how to optimize the love time given an arbitrary number of wives and given the exact period of each wife.